Báo cáo y học: " AIT test has no problem in the detection of anti-ribosomal P – authors’ response" docx

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In a recent article, Jearn and Kim assessed the ability of
indirect immunofluorescence on a novel human macrophage
cell line (IT-1) in an autoimmune target (AIT) assay to predict
the presence of anti-ribosomal P (anti-Rib-P) antibodies [1],
based on a previously described cytoplasmic and/or
nucleolar staining pattern [2]. Despite the clearance of the
AIT test by the South Korea Food and Drug Administration, to
the best of our knowledge this test is not widely used as a
screening method – neither is it approved by the Food and
Drug Administration (FDA) USA or is it a Communauté
Européenne (CE) certified method for the detection of anti-
nuclear antibodies. By contrast, many laboratories rely on
HEp-2 cell substrates that are widely available as FDA and
CE approved diagnostic kits from a variety of manufacturers.
In their study, Jearn and Kim identified sera with anti-Rib-P
reactivity based on a double immunodiffusion (ID) assay, and
then used these sera to determine the positivity and staining
patterns in the AIT test. This method raises concerns
because it is generally known that immunodiffusion is a
relatively insensitive technique for the detection of human
autoantibodies when compared with other techniques such
as ELISA and western immunoblotting (WB).
In an example relevant to the anti-Rib-P system, Bonfa and
colleagues clearly demonstrated that immunodiffusion has
very low sensitivity for the detection of anti-Rib-P antibodies
[3]. In their study, only 14% of anti-Rib-P-positive samples
identified by WB were detected by immunodiffusion. Another
study showed that ID exhibits significantly lower sensitivity
compared with a multiplex system: 63/130 (48.5%) samples

with at least one positive extractable nuclear antibody result
were negative by ID, and all 11 sera with anti-Rib-P reactivity
did not show a typical cytoplasmic staining pattern by indirect
immunofluorescence [4]. While the aforementioned studies
used HEp-2 cells as the substrate, there would be no reason
to believe that the AIT assay would perform remarkably better.
In the context of contemporary diagnostic assays such as
WB, ELISA or multiplexed addressable laser bead immuno-
assays, therefore, the data presented by Jearn and Kim do
not support the claim that the AIT test represents a sensitive
and reliable method for the detection of anti-Rib-P antibodies.
A systematic study is mandatory to compare the sensitivity
and specificity of the AIT test for the detection of anti-Rib-P
antibodies and other antibody specificities using a variety of
contemporary diagnostic platforms, not just ID. In addition to
anti-Rib-P, such a study could also include the evaluation of
anti-Jo-1, anti-SS-A (Ro60) and anti-Ro52 antibodies, which
have been shown to produce false negative results in indirect
immunofluorescence on HEp-2 cells [2,5].
Competing interests
MM is employed at Dr Fooke Laboratorien GmbH selling
autoantibody ELISAs. MJF receives honoraria from
ImmunoConcepts Inc. (Sacramento, CA, USA) for consulting
services.
References
1. Jearn L-H, Kim T-Y: AIT test has no problem in the detection of
anti-ribosomal P. Arthritis Res Ther 2009, 11:407.
2. Mahler M, Ngo JT, Schulte-Pelkum J, Luettich T, Fritzler MJ:
Limited reliability of the indirect immunofluorescence tech-
nique for the detection of anti-Rib-P antibodies. Arthritis Res

Ther 2008, 10:R131.
3. Bonfa E, Gaburo Júnior N, Tavares AV, Cossermelli W: Compari-
son of five methods for the detection of antiribosomal P
protein antibody. Braz J Med Biol Res 1994, 27:637-643.
4. Desplat-Jego S, Bardin N, Larida B, Sanmarco M: Evaluation of
Letter
AIT test has no problem in the detection of anti-ribosomal P –
authors’ response
Michael Mahler
1
and Marvin J Fritzler
2
1
Dr Fooke Laboratorien GmbH, Mainstraße 85, 41469 Neuss, Germany
2
Faculty of Medicine, HRB410B, University of Calgary, 3330 Hospital Dr NW, Calgary, Alberta, Canada T2N 4N1
Corresponding author: Marvin J Fritzler,
Published: 25 August 2009 Arthritis Research & Therapy 2009, 11:411 (doi:10.1186/ar2776)
This article is online at />© 2009 BioMed Central Ltd
See related letter by Jearn and Kim,
and related research by Mahler et al., />AIT = autoimmune target; anti-Rib-P = anti-ribosomal P; ELISA = enzyme-linked immunosorbent assay; ID = immunodiffusion; WB = western
immunoblotting.
Arthritis Research & Therapy Vol 11 No 4 Mahler and Fritzler
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the BioPlex 2200 ANA screen for the detection of antinuclear
antibodies and comparison with conventional methods. Ann
N Y Acad Sci 2007, 1109:245-255.
5. Kidd K, Cusi K, Mueller R, Goodner M, Boyes B, Hoy E: Detec-
tion and identification of significant ANAs in previously deter-

mined ANA negative samples. Clin Lab 2005, 51:517-521.